Apparatus for airless blast finishing



Sept. 17, 1968 E. H. WERN APPARATUS FOR AIRLEss BLAST FINISHING United States Patent O 3,401,489 APPARATUS FOR AIRLESS BLAST FINISHING Evert H. Wem, 20516 S. Kedzie, Olympia Fields, Ill. 60461 Filed Feb. 28, 1966, Ser. No. 530,450 4 Claims. (Cl. 51-9) ABSTRACT OF THE DISCLOSURE Blast finishing apparatus comprising a rotatable wheel of a one-piece, polymeric construction having a base portion and a plurality of wedge or sector shaped vanes extending from one surface of the base portion. The vanes are of a moderately fiexible material and are angularly spaced about the wheel and have radially inwardly converging side walls to define therebetween substantially parallel walled abradant chutes. Abrasive material is provided at the center of the wheel by means of a rotating auger and, as the Wheel is rotated, is delivered therefrom through the chutes and outwardly from the wheel.

This invention relates Igenerally to finishing apparatus and more particularly to apparatus for airless blast finishing.

In the cleaning of metal castings, forgings and other fabricated elements, as well as in the cold Working of metal surfaces, various particulate abradants are impelled at high velocity from the periphery of a bladed wheel. According to the conventional means for accomplishing this airless blast finishing, the wheel is formed of planar blades replaceably mounted between parallel disks; and gravity is employed to feed the abradant to the center of the Wheel. An auxiliary impeller is commonly used to deliver the abradant into the spaces between the vanes. The prior art wheel arrangements are expensive to construct; and the large, sector-shaped regions between the blades permit undesirable turbulence in the abradant at high wheel speeds with resultant unevenness in the pattern of expelled abradant.

Therefore, a general object of the present invention is to overcome these limitations of the prior art and to provide new and improved airless blast finishing apparatus.

Another object of the invention is to provide blast finishing apparatus Which promotes a uniform pattern of forcibly expelled abradant and which therefore produces a highly uniform surface finish on the treated Workpieces.

Still another object of the invention is to provide blast finishing apparatus that can be operated efficiently at comparatively low wheel speeds.

A further object of the invention is to provide a blasting Wheel arrangement that is easy and economical to construct.

These and other objects and features of the invention will become more apparent from a consideration of the following descriptions.

In order that the principles of the invention may be readily understood, a single embodiment thereof, `but to which the application is not to be restricted, is shown in the accompanying drawing wherein:

FIG. 1 is a side elevational view, partially in section, of blast finishing apparatus constructed in compliance with the present invention;

FIG. 2 is an elevational view taken along the line 2-2 of FIG. 1 to illustrate details of the blasting wheel;

FIG. 3 is a perspective view of the blasting wheel used in the apparatus of FIGS. 1 and 2;

FIG. 4 is an enlarged view of the central portion of FIG. 2, showing the discharge means used in delivering abradant to the blasting wheel; and

3,401,489 Patented Sept. 17, 1968 ICC FIG. 5 is a schematic view on a reduced scale, illustrating use of the apparatus of the invention in blast finishing parts being carried by a conveyor.

. Referring now in detail to the drawing, specifically to FIG. 1, blast finishing apparatus indicated generally by the reference numeral 410 is shown to comprise a blasting wheel 12 which is rotated about a horizontal axis by means of a suitably energized motor 14 and |which receives a supply of suitable abradant from a bin 16. The blasting wheel 12 comprises a rotatable base plate 18 and a plurality yof vanes 20 which will be described more fully hereinafter. The base plate 18 of blasting wheel 12 is secured to a -mounting plate 22 by means of screws 24 or other suitable fasteners; and the mounting plate 22 is, in turn, secured to an output shaft 26 of motor 14 by means of a coupling block 28 and one or more screw fasteners 30.

The blast finishing apparatus 10 additionally includes a machine frame which is indicated by the reference numeral 32; and this machine frame serves to support the motor 14 and a stationary cover plate 34 which confronts the bladed face of blasting wheel 12. A shroud or fender 36, which is also shown in FIG. 5, is conveniently mounted to the cover plate 34, although this shroud rnay also be secured independently to the machine frame 32.

In compliance with the features of the present invention, abradant from bin 16 is 'mechanically delivered to the blasting wheel 12; and continuing with reference to FIG. 1, a forced feeding unit 38 is shown to comprise a rotatable auger `40 which operates in a cylindrical casing 42, casing 42 opening vertically into the bottom of bin l16, passing through an aperture 44 in cover plate 34 and opening in a generally upward direction through an orifice unit 46 which is aligned radially with the blasting Awheel blades 20. The auger 40 is disposed Igenerally horizontally and in alignment with the rotational axis of blasting wheel 12. Furthermore, the auger 40 is rotated about its own longitudinal axis by a suitably energized drive motor 48, motor `48 having an output shaft 50 which is connected to the auger 40 through an end wall 52 of casing 42 by means of a shaft seal 54. Usefully, the cylindrical casing 42 is provided 4with a medially disposed support bracket 56.

Turning to a consideration of FIGS. 2 and 3 for a more detailed description of the blasting wheel 12, the vanes or blades 20 of the Iblasting wheel are arranged, in compliance with the features of the invention, to take a wedge or sector shape. Each of the vanes 20 has radially inwardly converging sidewalls 58 and 60; yand lsince the vanes are annularly spaced apart, confronting pairs of sidewalls 58 and 60 define therebetween substantially parallel-walled abradant chutes 62. The described arrangement of the vanes 20 and intermediate chutes 62 tends to preclude the development of turbulence in the radially exiting abradant and therefore promotes a more uniform pattern of expelled abradant. IIn further accord with the features of the invention, the radially inward ends of the vanes 20 are disposed radially outwardly from the center of base plate 18 which ydefines the rotational axis of the blasting wheel. This spacing of the inner ends of the vanes 20 establishes a hollow center 64 which receives the free end of cylindrical casing 42 and the orifice unit 46. This arrangement of the blasting wheel and cooperating auger feed insures an even supply of abradant to the chutes 62, even at comparatively low wheel speeds, and thus further promotes uniformity in the `abrading action. The term low wheel speed, as used herein, is intended to mean the peripheral speed of a blasting Wheel having an outside diameter of about eight to twelve inches rotated at an angular speed of about 1200 to 1500 revolutions per minute. As is shown in FIG. 4, the orifice unit 46 comprises a housing 66 which extends radially outwandly from the casing 42 into close proximity with the inner ends of 3 chutes 62. In addition, the radially outward end of housing 66 is provided with abradant-delivery orifice 68 which is sized and shaped appropriately to deliver a selected quantity of abradant to each of the chutes 62 as they rotate in turn passed the orifice unit. The delivery orifice may take elliptical or some other convenient shape.

In compliance with Aa yet further feature of the invention, the vanes 20 are fabricated `from a moderately exible, polymeric material; and such materials as polyurethane having a hardness of 70 to 90 durometer on the Shore A scale and nylon have proved eminently useful in this regard. The mild centrifugal flexing of vanes so fabricated has proved useful in promoting uniformity in the blast finishing operation. Moreover, when the vanes are fabricated from such polymeric material, the vanes 20 andthe base plate 18 may be advantageously fabricated to be integral, as by molding for example. Such integral fabrication develops substantial economies in the manufacture of the blasting Wheel, and it is recognized that the blasting wheel may be machined from a block of the polymeric material as well as being molded. The disclosed wedge or sector shape of the vanes 20 lends an acceptable degree of rigidity when the vanes are fabricated from polymeric material.

-For purposes of affording a more complete understanding of the invention, it is advantageous now to provide a brief description of the operation of the blast finishing apparatus 10. Referring to lFIG. 5 and assuming that motor 14 is rotating the blasting wheel 12 in the general direction indicated by arrow 70, a suitable abradant will :be delivered to the hollow center of the blasting wheel by the auger 40 of forced feeding unit 38. The particles of abradant will be expelled from the cylindrical casing of the unit 38 through the orifice 68 'and into the chutes 62 of the blasting wheel. As is suggested in IFIG. 5, the abradant passes into the chutes 62 at about 30 in advance of vertical. As the blasting wheel rotates, centrifugal energy is generated in the particles of abradant, and they exit from the outer tips of the vanes at an angle of about 120 subsequent to Vertical, as is suggested in the figure. The wheel 12 thus propels a blast 72 of abradant onto Workpieces 74 being carried by a conveyor 76 in the path indicated generally by arrow 78. The Workpieces 74 may be recycled or transmitted through the blast 72 in a single pass as is desired. In accordance with the descriptions given hereinabove, a highly uniform abra-ding action is achieved.

been shown and described, it should be understood, of course, that the invention is not limited thereto since many modifications may be made. it is therefore contemplated to cover by the present application any and all such modifications as fall within the true spirit :and scope of the appended claims.

The invention is claimed as follows:

1. Blast finishing apparatus comprising: a one-piece, rotatable wheel of a moderately flexible material, having integrally formed therewith and extending from one surface thereof, a plurality of wedge-shaped vanes, said vanes being angularly spaced yand having radially inwardly converging side Walls which define therebetween substantially parallel-walled abradant chutes through which abradant is radially outwardly discharged upon the rotation of said wheel.

2. Blast finishing apparatus as claimed in claim 1 Wherein said one-piece wheel is formed of a polymeric material.

3. Blast finishing apparatus `as claimed in claim 1 wherein the radially inward ends of said vanes are disposed outwardly from the center of rotation of said Wheel to form a hollow center portion for receiving abradant material therein to be distributed to said chutes therefrom upon the rotation of said wheel.

4. Blast finishing apparatus as claimed in claim 3 wherein the axis of rotation of said wheel is horizontally oriented and wherein abradant is fed from the hollow center of said wheel to said chutes -at `an angle approximately 30 degrees from the vertical in a direction opposite to that of the rotation of said Wheel and said abradant exits from said chutes at an angle of approximately degrees from the vertical in the direction of rotation of said wheel.

References Cited UNITED STATES PATENTS 859,863 7/1907 Young et al 51-9 1,953,566 4/1934 Peik 51-9 2,077,638 4/1937 Minich 51-9 2,092,962 9/1937 Fay et al 51-9 2,170,831 8/1939 Minich 51-9 2,225,482 12/ 1940 Mulvany 51-9 2,275,434 3/1942 Hobson 51-9 2,279,342 4/ 1942 Quinn 51-9 LESTER M. SWINGLE, Primary Examiner. 

